The importance of photolithography to the fabrication of microelectronic circuits is well known, and is exemplified by computer microprocessors, which at the current state of the art may contain millions of individual transistor control elements fabricated with submicron tolerances. The advent of photolithographic techniques has made possible mass production of such microprocessors and other types of circuits, which have revolutionized the computing and signal processing arts. The importance of the commercial mass production of such controllers cannot be overestimated, as sophisticated electronic control of everything from cameras and televisions to automobiles and aircraft has made the devices more user friendly and reliable.
It should be understood that a very narrow-band optical signal transmitted over optical waveguides can carry very high data rates consistent with high RF bandwidths. Optical control elements have certain advantages over electronic control elements, such as immunity to electromagnetic pulse and radio interference, and, in principle, should be as useful as their electronic counterparts, especially for severe environments and high RF bandwidths. However, optical controls have so far not reached the level of commercial importance enjoyed by the electronic controls. This may be due, in part, to the lack of processes for inexpensive mass production of optical control circuits, or microphotonic circuits.
Improved optical controllers, and improved fabrication methods for such controllers, are desired.